Ganthostat



Dec. 17, 1940. M. D. M GouN GNATHOSTAT Filed April 26, 1938 2 Sheets-Sheet 2 m a 5 mm wa y Patented Dec. 17, 1940 UNITED STATES PATENT OFFICE GNATHOSTA-T.

Maxwell Duncan MacGoun, Wellington, New Zealand Application April 26, 1938, Sjerial'No. 204,401 In New Zealand May 27-, 1937 7 Claims.

alies by Dr. Paul W. Simon, translated by Dr...

B. E. Lischer, and published in 1926 by the Stratford Company of Boston, Massachusetts, the particular art. to which this presentinvention relates is referred to as Gnathostatics and in such work the author describes in detail a gnathostat with ancillary apparatus which he had devised for use in the art in question.

The present invention has been devised with the object of providing improvements in or relating to a gnathostat of'the type above referred to, namely in the'takingof measurements bearing on orthodontic treatment and consists in an improved orthodontic measuring device and modelling guide. By the present invention certain disadvantages entailed in the use of such gnathostat are overcome while also the scope of the operation of a gnathostat has been widened.

With the gnathostat above referred to itwas necessary for the operator to support the gnathostat in position on the. patients head; thus not only considerably restricting his. movements, but adding to the diffi'culties of obtaining accurate adjustments of the requisite casts.

Furthermore such earlier apparatus was so constructed as to be extremely heavy with the result that'in use it was irksome and cumbersome to the patient.

Amongst other defects in construction may be mentioned the fact that it was difficult in the earlier apparatus to ensure that the stylus marks on the'impression indicated the locality 35 of the frontal plane. in its correct position, firstly because the operator had to use the stylus. from the orbital beam from below so that he could not readily observe the marking on the impres sion while secondly with the apparatus in question 40 it was diflicult to ensure that the impression and its tray were aligned from the supporting pillar in correct position.

Further in the earlier apparatus the construction was such that the tray was not capable of vertical movement up and down on the pillar with the result that the casts were made by raising the table towards the impression whereas in the present invention more positive means are employed by forcing the. poured impression down 50 the pillar onto the plaster mass onto the plane table.

The most important aspect of the present invention is, however, the provision for its more extensive application. In the earlier apparatus 55 it was not possible to retain the measurements of the Porion axis, that. is the axis between the. two Porion points, the Porion point being the upper edge: of the external auditory canal, as, to. remove theinstrument from; the patients head, at least one. of the pivoted ends of the 5 plane bow required adjusting movements, and the result was that on the removal of; the instrument fromthe-patientfs head the, length of the Porion axis was lost".

Rarticularly in the case/of certain malformations: of the: headv in. children-caused by malbreathing-it isimportant for-the specialist, consulted to have a chart of the Porion? axis so that he may be, aware at each consultation as to whether the condition in question is responding totreatment or. otherwise. v

According, therefore, to the present invention I have devised a gnathostat. which not only is of light construction, capable of. ready and accurate adjustment and is self-supporting on the, patients head, but on removal of the gnathostat from the .patients: head the length of theFPorion axis is not lost, thus enabling. an accurate chart to be plotted during the course of treatment.

These and other features more particularly pointed out in the. claimsconstitute the: present invention which will now in one constructional. embodiment be described with reference to the accompanying drawings in which,

Figure I is a plan of the semi-circular planebow with the-orbital beam in position, the frontal or orbital plane being represented by 3-3 Figure 2 is a side elevation of the assembled plane-bow, pillar, locating collar and impression tray in typical positions they may occupy on the patients head, the Frankfort or eye-ear plane and the frontal or 'orbita plane being represented by' AA and BB respectively,

Figure 3 is a plan of the impression tray, universal joint and adaptor,

Figured, is a front elevation of the plane-bow, orbital beam, pillar and impression tra-y assembly mounted on the base, with a stylus inserted in the" sheath of the orbital beam preparatory to marking the impression where the frontal or orbital plane intersects the dentition, the plane-bow being shown as though out through on the line C.-C, Figure 2,

Figure 5. is a section on the line D--D, Figure 4, the Frankfort or eye-ear plane, and, the frontal or orbital plane being represented by. A.A and BB respectively, and,

Figure 6' is a side elevation of the impression tray assembly and pillar inverted on the base 6 by aIset-screw a.

orbital ridges.

with the plane-table in such a position on the pillar that its upper surface corresponds with the Frankfort or eye-ear plane AA.

In the construction shown the semi-circular plane-bow comprises two preferably tubular curved arms I and 2 hinged together at 3, one of the arms I being connected by the connection 4 to a bow-collar 5 adapted to be held to a pillar The arms I and 2 are provided with upwardly projecting lugs I each having a hole therethrough to receive a threaded rod 8 which is provided with a head 9 at one end and a sleeve l0 and adjusting knob II at thethreaded end, a spring, I2 being, t

and have spherical hollows engaging the balls 34 and 39, to which such plates are held by means of a threaded bolt 42 engaging threads in the plate 4|, the head 43 of such bolt having wings 43a to disposed between the lugs.

The curved arms I and 2 have horizontal sleeves I3 secured thereunder at either sideof the pillar 6, and a spring-loaded threaded rod I4 is slidable I through each sleeve and is provided with an adjusting knob I5. The other end of each rod I4 ber- I6 having a flange -I'lso that the plane-bow will be supported by,-and the members I6 subnotches I8. I II I I At the outer end of each of the curved arms I and 2 there is provided a transverse sleeveIQ in which a spring-loaded threaded rod 20 is slidable, such threaded rod 20 having an adjusting knob Z'I on its threaded end and an ear-hole engaging member 22 whichis preferably about 1 in diameter, at'the other end; I I

The curved arms [and 2 are bent downwardly V at theends farthest from the hinge 3 so thatthe axes of the rods I4 are as nearly aspossible in the same plane asthe topsof the ear-hole engaging members. 22, this plane coinciding substan tially,on the patientshead, withthe Frankfort I I provide an orbital beam comprising fiat,

strip 23 .having spring clips at'each .end so that it may be clipped rigidly to the curved arms I and2. I v

The spring clipscomprise short strips24 hinged at 25 to the stripv23 and having preferablyphosphor-bronze strips 26 projectingupwardlyat their outer ends, such spring strips 26,.being soformed that by bringing the Strips 24 upwardly thespring l strips 25 will clip, over theendsoi the strips 23 which will be. thus securely: heldiytoythe armsj I and 2. I

The strip projecting plates or flanges 21 which, when the frontal-plane recording members I6 are inverted as shown in Figures 4; and 5 can bebrought into engagement with the vertical faces of such members I6 so that, as the frontal plane isin' line with such vertical faces,the outer surfaces of the other end at right angles to the axisof such pin.

The sheath 30 is partly accommodated 'in'the.

recess 28. I

I provide a stylus the sheath 30 so as to mark the intersection of the dentition by the frontal? or orbital? plane.

The pillar s, is provided with arm side Ba adapted to be engaged by the set-screws of the various components so. thatisuchv compohe'nts will be correctly located about such pillar by tighten- 23 is provided with two downwardlys 32 adapted to bii srtea in ing the appropriate set-screws.

I provide an impression tray 33 connected by a universal joint to an adaptor 35 having a slot 36 and a set-screw 31 so that the impression tray may be readily removed from, or attached to, the pillar 6.

The universaljoint is constructed in the following manner:

The impression tray 33 is provided with a projection 33a having a ball 34 at its outer end, and the adaptor 35 has an extension 38 which is ballshaped at its outer end 39.

Two clamping plates 40 and 4| are provided,

facilitate tightening such bolt, and washers 44 being provided.

I provide a heavybase 45Hhavi'nga collar m which the pillar 6, may be secured by; the setscrew 41.

I also provide a plane-table 48,, Figure 6 ,1'hav.-

ing a collar 49 and set-screw 50; such table being oblong and in use being placed on the pillar 6 in place of the plane-bowand with its surface ,5! coinciding with the ,Frankiort plane AI-A so that in the cephalometric cast, whichis built up,

on such table, the,Frankfort plane is represented by a flat surface: 7 I, I provide a locating collar- 52 havingqa ;setscrew 53, such collar being employed to locatethe impression tray assembly, plane-bowI assembly and plane-table on the pillar Gin the various frontal or orbital plane, and adjusting "the knobs I I and 2| according to thedistance between the ear-holes and according to the pupillar width which is'recorded by the, spacing of the notches I8. I Q i It will be understood that, by -'adjusting the knob ll, both the distance betweenIthe-ear-hole engaging members 22 and the distance between the notches I8 will be adjusted, while adjustment of the knobs 2I will, affect, the relativespacings of the ear -holeengaging members 22and the notchesIBs.

,I do not consideriit essential to'record'exactly the pupillar width,'and, because itis essential' that the adjustment of the" knobs ;2I is...always. such that the members 22 onlypresslightly in, the ear-holes and maybe moved sufllciently,

against the pressure of the springs and-{magma 1) to release such members 22 from, the ear-holes,

it may be, necessary insome cases to laterally displace the 'notches I8 relatively to adjustingthe knob II. t t

When the adjustment is correct, the planebow is supportedbythe flanges I 1'0: thejrontalh pup l by plane recording members I6 resting on the tops.

of the infra-orbital ridges.

The plane-bow is now removed from the head and the pillar 6 isthen placed in the bow-collar 5 and the set-screw 5a is tightened;

The locating collar. 52 is moved up the pillar.

preferably so as; to contact with the lower end the impression tray 33 is in position in the mouth,-

the operator makes sure that the universal joint is free and that the set-screw 31- is withdrawnsufficiently to allow free access of the pillar 6 into the slot 36.

- When the impression compound saw is wellset,

the patient'is asked-to bring the lower teeth into contact with the tray 33 to assist in retaining it in position.

The plane-bow assembly is then replaced onmembers-22' and frontal-plane recording members H5 in correct position, the tray-adaptor 35 is placed on the pillar 6 and the set-screw 31 is tightened.

As the plane-bow and impression tray 33 will now be in their correct relative positions, the impression tray 33 is secured by tightening the universal-joint bolt 42.

The locating collar 52 is then loosened and moved down so as to contact with the trayadaptor 35 and is tightened in this position on the pillar 6.

The various members of the assembly may then have the relative positions shown in Figure 2.

The set-screw 3'! is then loosened sufficiently to permit sideways removal of the pilar 6 from the adapter 35 and the plane-bow, pillar 6 and locating collar 52 are then readily removable from the patients head and from the impression tray assembly by withdrawing the ear-hole engaging members 22 from the ear-holes by traction on the adusting knobs 2|.

The pillar 6 is then fixed in the base collar 46 and the set-screw 41 is tightened, the impression tray assembly being then replaced in its former position on the pillar.

The orbital beam is placed in position across the plane-bow and is secured in position in the manner hereinbefore described after bringing the plates or flanges 21 into contact with the vertical faces of the frontal-plane recording members It.

The stylus 32 is then inserted in the sheath so, as shown in Figures 4 and 5, and marks are carefully scratched on the impression compound 33a sufficiently to show up on the cast. These marks indicate the intersection of the dentition by the frontal or orbital plane, and may take the form of a line or a series of pin-pricks by swinging movement of the stylus across the line of intersection on the impression.

The locating collar 52 is then loosened and moved to contact with the bow collar 5, the setscrew 5a is loosened and the plane-bow is then removed from the pillar 6.

The plane table 48 is placed on the pillar in place of the plane-bow and with its surface 5| towards the impression 33a.

The whole assembly is then inverted in the stand as shown in Figure 6, the locating collar 52 is moved upwardly on the pillar so as to contact with the adaptor 35 and the impression tray assembly is removed. 7

A quantity of mixed plaster of Paris is now poured into the impression and a soft plaster mass is placed on the plane table which is preferably coated with Vaseline or the like, and the impression tray assembly is placed on the pillar 6 and forced down onto the plaster mass until the adaptor 35 again engages the locating collar 52. I

After the plaster hasset the-cast thus obtained of the upper dentition is-separa'ted from the impression and may be finished and markedina similar manner to.- that disclosed in the work entitled Fundamental Principles of a Systematic Diagnosis' of Dental Anomalies hereinbefore referred to, the lower cast being made in the usual manner.

The distance between the ear-hole engaging members 22-; the distance'between the notches I85 and the distance between the ear-hole engaging members 22 and the frontal plane, may be recorded on a card or the like such as by constructing a quadrilateral figureillustrating these measurements, a record'being thus kept of the cranial dimensions ateachstage of development or treatment;

It will be realised that the comparison of these charts with the cephalometric casts made at corresponding stages will yield valuable data.

I claim:

1. A gnathostat of the type referredto including a pillar, a plane-bow comprising two arms hinged together and in the same plane, a collar extending from one of such arms and having its axis perpendicular to the plane thereof, means for detachably securing the plane-bow to the pillar in any desired selected position longitudinally thereof, means to adjust the relative positions of the arms about the hinge, transversely adjustable ear-hole engaging members associated with each arm, springs to hold such members in the ear-holes, and substantially longitudinally adjustable frontal plane locating members associated with such arms and adapted to engage the infra-orbital ridges in such a manner as to assist in supporting the plane-bow on the head of the patient or subject.

2. A gnathostat of the type referred to including a pillar, a plane-bow comprising two arms hinged together and in the same plane, a collar extending from one of such arms, and having its axis perpendicular to the plane of such arms, means for detachably securing the plane-bow to the pillar in any desired selected position longitudinally thereof, means to adjust the relative position of the arms about the hinge, transversely adjustable means associated with each arm at a distance from the hinge for engaging the earholes and longitudinally adjustable means associated with such arms for engaging the infraorbital ridges.

3. A gnathostat as claimed in claim 2 wherein the free extremities of the plane-bow arms are curved away from the plane of the major portion of the plane-bow and the ear-hole engaging members are carried by these extremities of the plane-bow so that they are disposed slight- 1y below the level of the plane-bow.

4. A gnathostat of the type referred to comprising a supporting pillar, a base in which either end of said pillar may be mounted for holding it in upright position, a plane-bow and an impression tray independently detachably securable to and adjustable longitudinally of the pillar, an orbital beam for mounting on the planebow and a stylus carried by the orbital beam for marking its path on an impression in the tray, said pillar being reversible on its base so that the stylus may be operable to trace its path on the impression from above.

5. Agnathostat as claimed in claim 4 wherein the side of the pillar against which the securing means of all the detachable parts of the an: paratus work, is flat, whereby they may beindividually removed and replaced in the same relative adjusted relationship. i

6. An improved orthodontic measuring device including a plane-bow comprising two arms hinged together in the same plane, two ear-hole engaging members carried by said arms adjacent to the free ends thereof and movable inwardly and outwardly with respect to each other, springs for holding said members in ear-hole engaging positions, adjustable means for securing said members against further inward movement with respect to said positions, and two frontal plane recording members adapted to engage the infraorbital ridgesin such a manner as to support the plane-bow on the head of the patient or subect.

7. An improved orthodontic measuring device including a plane-bow comprising two arms plane-bow on the head of the patient or subject,

and means for adjusting said plane-bow arms on their hinges with respect to each other whereby the relation ofthe frontal plane recording members may be adjusted laterally and substantially correctly located relative to the infraorbital ridges of the patient or subject.

MAXWELL DUNCAN MACGOUN. 

